• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.5
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• pp.232-237
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• 2005

In this paper, we fabricated $CO_2$ gas sensor based on the MEMS infrared sensor and characterized its electrical and $CO_2$-sensing properties. The fabricated $CO_2$ gas sensor by MEMS technique has many advanges over NDIR(nondispersive) $CO_2$ sensor such as monolithic fabrication, very high selectivity on $CO_2$, low power consumption and compact system. Microbolometer by surface micromachining was fabricated for gas detector and $CO_2$ filter chip by bulk micromachining was fabricated for signal referencing. By using the proposed and fabricated gas sensor, we are expected to measure $CO_2$ concentration more accurately with high reliability.

• Analytical Science and Technology
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• v.13 no.2
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• pp.222-228
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• 2000

A detector for monitoring carbon monoxide (CO) in ambient air by nondispersive infrared (NDIR) spectroscopy has been developed and investigated its sensitivity and stability. The essential parts of the absorption cell are three spherical concave mirrors so as to improve the sensitivity by increasing the light path length in the cell. The radius and center of curvature of mirrors and position in the cell was calculated by computer simulation in order that the light path length may be 16m into the 50cm cell. The number of traversals and optical path properties were confirmed by laser beam alignment in transparent absorption cell. The photoconductive type lead selenide (PbSe) was used as CO sensing material, which was cooled to increase the responsibility by thermoelectric cooling method. The detection limit and span drift of the developed CO detector was 0.24ppm and 0.03ppm(v/v) respectively.

• Journal of the Korean Institute of Gas
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• v.12 no.4
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• pp.63-68
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• 2008

This paper describes about the simulation and the experimental results of optical cavity with curved mirror surface and vertical mirror surface to improve the light intensity and efficiency of the optical sensors. When we use the vertical mirror surface, the distribution of light reached to the filter surface of detector shows an elliptical shape. Whereas, the curved mirror surface focuses the light into circular shape. Therefore, due to focusing effects in case of using curved mirror surface, the light intensity per unit area has been improved. Consequently, the output voltage of gas sensor has been expected to increase. Based upon the simulation, the experiment of gas sensor has been conducted with $CO_2$ gas from 0ppm to 2,500 ppm at 250 ppm step and $25^{\circ}C$, 45%R.H. ambient. The output voltage of gas sensor that has a curved mirror surface increases approximately 200 mV than that of vertical mirror surface.

• Journal of Animal Science and Technology
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• v.53 no.5
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• pp.475-480
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• 2011

This study was conducted to investigate the effects of different feeding level of TDN (Total Digestible Nutrients) on the generation of main greenhouse gases such as carbon dioxide and methane in Hanwoo cows. The diet TDN (kg) adjusted to achieve ADG of 0 g/day (Control), 200 g/day (T1), and 400 g/day (T2) of the maintenance level TMR (Total Mixed Ration) delivered twice a day at 08:30 and 17:30. Cow are housed in a respiration chamber and the environmental temperature was maintained at $20^{\circ}C$. The gases were measured for 24 hours using the multi-detector instrument Mamos-300. The analyzed methane emissions of T1 and T2 were 33.5% and 69.6% higher than control, respectively, and the carbon dioxide emissions were 21.1% and 40.6% higher than control. Also, the hourly pattern of carbon dioxide and methane production were showed very similar emission. Gas production showed peak after 1 hour of feeding and this gap was wider in the afternoon than in the morning hours. It is clearly conducted that $CO_2$ and $CH_4$ emissions were different by limited intake levels of feed.